Wellbores are sometimes drilled into subterranean formations containing hydrocarbons to allow recovery of the hydrocarbons. During the drilling and production of a hydrocarbon bearing formation, various procedures may be performed that involve temporarily isolating fluid flowing between the surface of a wellbore and the formation through a wellbore tubular. Such procedures can include flow control operations, completion operations, and/or interventions. Various valves, including safety valves, may be used during these procedures to control the flow of fluid through the wellbore tubular.
Safety valves may be inserted deep in a well, as deep as 10,000 feet or more for example. Operating safety valves at these depths poses several problems, including delays in valve closure time and potential damage to components of the safety valve. A typical safety valve is actuated when a pressure differential in a control line of the safety valve displaces a piston, which in turn displaces a flow tube opening a flapper. The control line is generally designed to withstand a pressure greater than the pressure needed to compress a biasing device, for example a spring, which typically requires a relatively high pressure rating for the control line.